CN116130569A - High-efficiency light-emitting diode and preparation method thereof - Google Patents

Abstract

The invention provides a high-efficiency light-emitting diode and a preparation method thereof, wherein the high-efficiency light-emitting diode comprises a substrate, and a buffer layer, an undoped GaN layer, a composite N-type GaN layer, a multiple quantum well layer, an electron blocking layer and a P-type GaN layer which are sequentially deposited on the substrate; the composite N-type GaN layer comprises a first Si doped GaN layer, a SiN layer and a superlattice layer which are sequentially deposited on the undoped GaN layer, wherein the superlattice layer comprises an Si doped AlN layer, an InN layer and a second Si doped GaN layer which are sequentially and alternately deposited according to a preset period, and the concentration of Si doped in the first Si doped GaN layer is greater than that of Si doped in the second Si doped GaN layer. According to the invention, the composite N-type GaN layer is inserted between the undoped GaN layer multiple quantum well layers, so that the stress between the substrate and the epitaxial layer is reduced, the line defect and stacking fault occur at the interface of the multiple quantum well layers, and the luminous efficiency of the light-emitting diode is improved.

Description

A high-efficiency light-emitting diode and preparation method thereof

Technical Field

The invention relates to the field of optoelectronic technology, and in particular to a high-efficiency light-emitting diode and a preparation method thereof.

Background Art

In recent years, gallium nitride (GaN) materials, as third-generation direct bandgap semiconductor materials, have been widely used in industry. Especially in the field of LED lighting, GaN-based blue LEDs have the characteristics of high brightness, high energy efficiency and long life, demonstrating their potential to replace existing lighting equipment.

The conductivity of intrinsic GaN crystal is relatively low. Currently, the conductivity of GaN can be improved through effective doping. When current is injected, electrons can be continuously generated to participate in the radiation recombination in the active area. The doping elements are generally required to be close to the atomic radius of GaN and still maintain a certain stability at the growth temperature. In the epitaxial growth of GaN, the most commonly used n-type doping element is Si, and the doping source is SiH _4. The doping concentration can be achieved by adjusting the flow rate of SiH ₄ .

However, due to the large lattice mismatch and difference in thermal expansion coefficient between the substrate material and the GaN crystal, there is a large compressive stress in the epitaxial layer of the light-emitting diode. Stress release will cause line defects and stacking faults in the active area, affecting the reliability and light-emitting characteristics of the device.

Summary of the invention

Based on this, the purpose of the present invention is to provide a high-efficiency light emitting diode and a preparation method thereof to solve the problems existing in the prior art.

A first aspect of the present invention provides a high-efficiency light-emitting diode, comprising a substrate, and a buffer layer, an undoped GaN layer, a composite N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer sequentially deposited on the substrate; the composite N-type GaN layer comprises a first Si-doped GaN layer, a SiN layer and a superlattice layer sequentially deposited on the undoped GaN layer, the superlattice layer comprises a Si-doped AlN layer, an InN layer and a second Si-doped GaN layer alternately deposited in sequence according to a preset period, wherein the concentration of Si doped in the first Si-doped GaN layer is greater than the concentration of Si doped in the second Si-doped GaN layer.

The beneficial effects of the present invention are as follows: the present invention provides a high-efficiency light-emitting diode, wherein a composite N-type GaN layer is inserted between an undoped GaN layer and a multi-quantum well layer, wherein the composite N-type GaN layer comprises a first Si-doped GaN layer, a SiN layer and a superlattice layer sequentially deposited on the undoped GaN layer, the superlattice layer comprises a Si-doped AlN layer, an InN layer and a second Si-doped GaN layer sequentially deposited alternately according to a preset period, the concentration of Si doped in the first Si-doped GaN layer is greater than the concentration of Si doped in the second Si-doped GaN layer, and since the resistivity of the composite N-type GaN layer is higher than that of the P-type GaN layer, therefore, depositing a first Si-doped GaN layer with a higher concentration on the undoped GaN layer can generate a large amount of electrons to supply the multi-quantum well layer, and perform radiation recombination with holes in the multi-quantum well layer, thereby reducing the overall density of the composite N-type GaN layer. The resistivity of the body is improved, and the light-emitting effect of the diode is improved. Furthermore, the deposited SiN layer can form a dense SiN film on the first Si-doped GaN layer, further reducing the dislocation defects that penetrate the first Si-doped GaN layer, and reducing the dislocation defects that extend into the multi-quantum well layer and affect the light-emitting efficiency. The superlattice layer can effectively release the stress between the composite N-type GaN layer and the multi-quantum well active layer, reduce the line defects and stacking faults at the interface of the multi-quantum well layer, and improve the crystal quality. Furthermore, the Si-doping concentration of the second Si-doped GaN layer in the superlattice layer is less than the Si-doping concentration of the first Si-doped GaN layer, which can provide a movement channel for the electrons generated by the first Si-doped GaN layer, so that the electrons can effectively move to the multi-quantum well layer. In addition, the interface voltage between the second Si-doped GaN layer and the multi-quantum well layer can be reduced, further improving the crystal quality.

Preferably, the thickness of the first Si-doped GaN layer is 1um-5um, the thickness of the SiN layer is 1nm-100nm, and the thickness of the superlattice layer is 50nm-500nm.

Preferably, a thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1:1:10-10:1:50.

Preferably, the preset period is 1-20.

Preferably, the concentration of Si doped in the first Si-doped GaN layer is 1×10 ¹⁸ atoms/cm ³ -1×10 ²⁰ atoms/cm ³ , and the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 1×10 ¹⁷ atoms/cm ³ -1×10 ¹⁹ atoms/cm ³ .

Another aspect of the present invention further provides a method for preparing the above-mentioned high-efficiency light-emitting diode, comprising the following steps:

providing a substrate;

Depositing a buffer layer, a non-doped GaN layer, a composite N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer in sequence on the substrate;

The composite N-type GaN layer includes a first Si-doped GaN layer, a SiN layer and a superlattice layer sequentially deposited on the undoped GaN layer, and the superlattice layer includes a Si-doped AlN layer, an InN layer and a second Si-doped GaN layer alternately deposited on the SiN layer in sequence according to a preset period, wherein the concentration of Si doped in the first Si-doped GaN layer is greater than the concentration of Si doped in the second Si-doped GaN layer.

Preferably, the growth atmosphere during the deposition and growth of the first Si-doped GaN layer is a mixed gas with a composition ratio of N ₂ /H ₂ /NH ₃ of 1:1:10-1:5:10.

Preferably, the growth atmosphere during the deposition growth of the superlattice layer is a mixed gas with a N ₂ /NH ₃ composition ratio of 1:5-5:1.

Preferably, the deposition growth temperature of the first Si-doped GaN layer is 1000°C-1200°C, the deposition growth temperature of the SiN layer is 900°C-1100°C, and the deposition growth temperature of the superlattice layer is 800°C-1000°C.

Preferably, the growth pressure during the growth of the composite N-type GaN layer is 50 torr-300 torr.

Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a high-efficiency light-emitting diode provided by the present invention;

FIG. 2 is a flow chart of a method for preparing a high-efficiency light-emitting diode provided by the present invention.

Description of main component symbols:

The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings.

DETAILED DESCRIPTION

In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and/or" used herein includes any and all combinations of one or more of the related listed items.

The present invention provides a high-efficiency light-emitting diode and a preparation method thereof. A composite N-type GaN layer is inserted between an undoped GaN layer and a multi-quantum well layer, wherein the composite N-type GaN layer comprises a first Si-doped GaN layer, a SiN layer and a superlattice layer sequentially deposited on the undoped GaN layer, the superlattice layer comprises a Si-doped AlN layer, an InN layer and a second Si-doped GaN layer sequentially deposited alternately according to a preset period, the concentration of Si doped in the first Si-doped GaN layer is greater than the concentration of Si doped in the second Si-doped GaN layer, the composite N-type GaN layer is used to reduce line defects and stacking faults at the interface of the multi-quantum well layer, reduce the interface voltage between the second Si-doped GaN layer and the multi-quantum well layer, and improve the crystal quality.

Specifically, referring to Figure 1, the high-efficiency light-emitting diode provided in an embodiment of the present invention includes a substrate 10, and a buffer layer 20, an undoped GaN layer 30, a composite N-type GaN layer 40, a multi-quantum well layer 50, an electron blocking layer 60 and a P-type GaN layer 70 sequentially deposited on the substrate 10; the composite N-type GaN layer 40 includes a first Si-doped GaN layer 41, a SiN layer 42 and a superlattice layer 43 sequentially deposited on the undoped GaN layer 30, and the superlattice layer 43 includes a Si-doped AlN layer 431, an InN layer 432 and a second Si-doped GaN layer 433 alternately deposited on the SiN layer 42 according to a preset period, wherein the concentration of Si doping in the first Si-doped GaN layer 41 is greater than the concentration of Si doping in the second Si-doped GaN layer 433. Preferably, the concentration of Si doped in the first Si-doped GaN layer is 1×10 ¹⁸ atoms/cm ³ -1×10 ²⁰ atoms/cm ³ , and the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 1×10 ¹⁷ atoms/cm ³ -1×10 ¹⁹ atoms/cm ³ .

Specifically, the substrate 10 can be selected from one of sapphire substrate, _SiO2 sapphire composite substrate, silicon substrate, silicon carbide substrate, gallium nitride substrate, and zinc oxide substrate; sapphire substrate has mature preparation technology, high cost performance, easy cleaning and processing, good stability at high temperature, and is widely used. Therefore, a sapphire substrate is selected. However, there are very large defects on the surface of the sapphire substrate. The defects of the epitaxial layer directly deposited on the substrate are easy to extend to the multi-quantum well layer. The multi-quantum well layer is the active layer of the light-emitting diode. The defects extending to the multi-quantum well layer will directly affect its light-emitting effect. Therefore, before depositing the epitaxial layer on the substrate, a buffer layer 20 needs to be deposited on the substrate 10 to reduce the defects on the surface of the sapphire substrate to a certain extent. Specifically, the buffer layer 20 can be an AlN buffer layer with a thickness of 10nm-15nm.

The non-doped GaN layer 30 is deposited on the buffer layer 20, and the thickness of the non-doped GaN layer 30 is 1um-5um. The thicker non-doped GaN layer 30 can effectively release the compressive stress between the light-emitting diodes, improve the crystal quality, and reduce reverse leakage. However, at the same time, the increase in the thickness of the GaN layer consumes more Ga source materials, greatly increasing the epitaxy cost of the light-emitting diode (LED). Therefore, further, in order to take into account the quality and production cost of the light-emitting diode, preferably, the non-doped GaN layer 30 is 2um-3um.

The main function of the composite N-type GaN layer 40 in the LED is to further reduce the defects between crystals and provide sufficient electrons for the LED to emit light and enable the electrons to move smoothly to the multi-quantum well layer and radiate and recombine with the holes in the multi-quantum well layer; further reducing the defects of the crystal can improve the quality of the crystal, and providing sufficient electrons to recombine with the holes in the multi-quantum well layer can effectively improve the overall luminous efficiency of the LED. Specifically, the composite N-type GaN layer 40 includes a first Si-doped GaN layer 41, a SiN layer 42 and a superlattice layer 43 sequentially deposited on the undoped GaN layer 30. The thickness of the first Si-doped GaN layer is 1um-5um, the thickness of the SiN layer is 1nm-100nm, and the thickness of the superlattice layer is 50nm-500nm. Since the resistivity of the composite N-type GaN layer 40 is higher than that of the transparent electrode on the P-type GaN layer 70, it is the main factor affecting the device current expansion and increasing the series resistance. Therefore, the light-emitting diode provided by the present invention deposits a first Si-doped GaN layer 41 with a relatively high concentration on the non-doped GaN layer 30, which can generate a large number of electrons to supply the multi-quantum well layer 50, and perform radiation recombination with the holes in the multi-quantum well layer 50, thereby reducing the overall resistivity of the composite N-type GaN layer 40 and improving the light-emitting effect of the diode. In addition, the first Si-doped GaN layer 41 is deposited to a thickness of 1um-5um. The higher thickness can increase the current expansion, reduce the series resistance of the composite N-type GaN layer 40, and reduce the operating voltage of the light-emitting diode, and can also release the compressive stress inside the composite N-type GaN layer through stacking faults, reduce line defects, improve crystal quality, and reduce reverse leakage current.

Furthermore, by depositing the SiN layer 42 on the first Si-doped GaN layer 41, a dense SiN film can be formed on the first Si-doped GaN layer 41, blocking the dislocation defects penetrating the first Si-doped GaN layer 41, further reducing the dislocation defects extending to the multi-quantum well layer 50, and affecting the luminescence efficiency of the multi-quantum well layer 50. In addition, the superlattice layer 43 includes a Si-doped AlN layer 431, an InN layer 432, and a second Si-doped GaN layer 433 alternately deposited on the SiN layer 42 in sequence according to a preset period. Preferably, the thickness ratio of the Si-doped AlN layer, the InN layer, and the second Si-doped GaN layer is 1:1:10-10:1:50, and the period of alternating deposition is 1-20. The superlattice layer 43 can effectively release the mismatch stress between the composite N-type GaN layer 40 and the multi-quantum well layer 50, improve the incorporation efficiency of electrons and holes in the multi-quantum well layer 50, improve the crystal quality, and reduce the non-radiative recombination efficiency of the multi-quantum well layer 50. Furthermore, the Si-doping concentration of the second Si-doped GaN layer in the superlattice layer is lower than that of the first Si-doped GaN layer. The lower Si-doped GaN layer can provide a movement channel for the electrons generated by the first Si-doped GaN layer, so that the electrons can effectively move to the multi-quantum well layer, and can also reduce the interface voltage between the second Si-doped GaN layer and the multi-quantum well layer, thereby further improving the crystal quality.

The multi-quantum well layer 50 includes alternately deposited InGaN quantum well layers and AlGaN quantum barrier layers, with a deposition period of 6 to 12, wherein the thickness of a single-layer InGaN quantum well layer is 2nm to 5nm, the thickness of a single-layer AlGaN quantum barrier layer is 5nm to 15nm, and the Al component is 0.01 to 0.1. The electron blocking layer 60 is an _{Al a} In _b GaN layer, with a thickness of 10nm to 40nm, wherein the value of a ranges from 0.005 to 0.1, and the value of b ranges from 0.01 to 0.2; the P-type GaN layer 70 has a thickness of 10nm to 50nm, and can be doped with Mg, with a Mg doping concentration of 1×10 ¹⁹ atoms/cm ³ to 1×10 ²¹ atoms/cm ³ .

Please refer to FIG. 2 , which is a method for preparing a high-efficiency light-emitting diode in an embodiment of the present invention, which is used to prepare the above-mentioned light-emitting diode. Specifically, the method for preparing a high-efficiency light-emitting diode provided by the present invention includes steps S10-S70.

Step S10, providing a substrate;

Specifically, the substrate can be selected from one of a sapphire substrate, a _SiO2 sapphire composite substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, and a zinc oxide substrate. Sapphire is currently the most commonly used GaN-based LED substrate material. The biggest advantage of the sapphire substrate is that the technology is mature, the stability is good, and the production cost is low. Therefore, in this embodiment, sapphire is selected as the substrate.

Step S20, depositing a buffer layer on the substrate;

Specifically, physical vapor deposition (PVD) can be used to deposit a buffer layer on the substrate, and the thickness of the buffer layer is 15nm-20nm. In the present embodiment, an AlN buffer layer is used. The AlN buffer layer provides a nucleation center with the same orientation as the substrate, releases the stress caused by the lattice mismatch between the epitaxial GaN material and the substrate and the thermal stress caused by the mismatch of thermal expansion coefficients, provides a flat nucleation surface for epitaxial growth, reduces the contact angle of its nucleation growth, and enables the island-like grown GaN grains to be connected into a surface within a smaller thickness, thereby transforming into two-dimensional epitaxial growth.

Step S30, pre-treating the substrate on which the buffer layer has been deposited.

Specifically, the sapphire substrate on which the buffer layer has been deposited is transferred to the A7 Metal-organic Chemical Vapor Deposition (MOCVD) equipment of Zhongwei. In the MOCVD equipment, one of high-purity _H2 (hydrogen), high-purity _N2 (nitrogen), and a mixed gas of high-purity _H2 and high-purity _N2 can be used as a carrier gas, high-purity _NH3 as an N source, trimethylgallium (TMGa) and triethylgallium (TEGa) as gallium sources, trimethylindium (TMIn) as an indium source, trimethylaluminum (TMAl) as an aluminum source, silane ( _SiH4 ) as an N-type dopant, and bis(cyclopentadienyl)magnesium ( _CP2Mg ) as a P-type dopant can be used for epitaxial growth.

Specifically, the substrate on which the buffer layer has been deposited is treated in a _H2 atmosphere for 1 min-10 min at a treatment temperature of 1000°C-1200°C, and then nitrided to improve the crystal quality of the buffer layer and effectively improve the crystal quality of the subsequently deposited GaN epitaxial layer.

Step S40: depositing a non-doped GaN layer on the buffer layer.

After the substrate on which the buffer layer is deposited is nitrided, a non-doped GaN layer is deposited in an MOCVD device, and high-purity _NH3 is used as an N source, and trimethyl gallium (TMGa) and triethyl gallium (TEGa) are used as gallium sources; the growth temperature of the non-doped GaN layer is 1050°C-1200°C, the pressure is 50torr-500torr, and the thickness is 1um-5um; preferably, the growth temperature of the non-doped GaN layer is 1100°C, and the growth pressure is 150torr. The growth temperature of the non-doped GaN layer is high and the pressure is low, and the prepared GaN crystal quality is better. In addition, as the thickness of the GaN increases, the compressive stress in the non-doped GaN layer will be released through stacking faults, thereby reducing line defects, improving crystal quality, and reducing reverse leakage. However, increasing the thickness of the GaN layer consumes a large amount of Ga source materials, which greatly increases the epitaxial cost of the LED. Preferably, the growth thickness of the non-doped GaN is 2um-3um, which not only saves production costs, but also has a higher crystal quality of the GaN material.

Step S50, depositing a composite N-type GaN layer on the undoped GaN layer.

Specifically, after depositing the undoped GaN layer, a composite N-type GaN layer is continuously deposited in the MOCVD device, wherein the composite N-type GaN layer includes a first Si-doped GaN layer, a SiN layer, and a superlattice layer sequentially deposited on the undoped GaN layer, and the superlattice layer includes a Si-doped AlN layer, an InN layer, and a second Si-doped GaN layer alternately deposited in sequence according to a preset period, wherein the concentration of Si doped in the first Si-doped GaN layer is greater than the concentration of Si doped in the second Si-doped GaN layer.

Specifically, the deposition thickness of the first Si-doped GaN layer is 1um-5um, the deposition thickness of the SiN layer is 1nm-100nm, the deposition thickness of the superlattice layer is 50nm-500nm, the deposition thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1:1:10~10:1:50, preferably, the deposition thickness of the first Si-doped GaN layer is 2.5um, the deposition thickness of the SiN layer is 65nm, the deposition thickness of the superlattice layer is 200nm, and the deposition thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 5:1:40. The cycle of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1-20, preferably, the cycle of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 6. The Si doping concentration in the first Si-doped GaN layer is 1×10 ¹⁸ atoms/cm ³ -1×10 ²⁰ atoms/cm ³ , and the Si doping concentration in the Si-doped AlN layer and the second Si-doped GaN layer is 1×10 ¹⁷ atoms/cm ³ -1×10 ¹⁹ atoms/cm ³ ; preferably, the Si doping concentration in the first Si-doped GaN layer is 2×10 ¹⁹ atoms/cm ³ , and the Si doping concentration in the Si-doped AlN layer and the second Si-doped GaN layer is 6×10 ¹⁷ atoms/cm ³ .

Further, the deposition growth temperature of the first Si-doped GaN layer is 1000°C-1200°C, the deposition growth temperature of the SiN layer is 900°C-1100°C, and the deposition growth temperature of the superlattice layer is 800°C-1000°C; preferably, the deposition growth temperature of the first Si-doped GaN layer is 1100°C, the deposition growth temperature of the SiN layer is 1000°C, and the deposition growth temperature of the superlattice layer is 900°C. The growth atmosphere during the deposition and growth of the first Si-doped GaN layer is a mixture of _N2 / _H2 / _NH3 with a ratio of 1:1:10-1:5:10; the growth atmosphere during the deposition and growth of the superlattice layer is a mixture of _N2 / _NH3 with a ratio of 1:5-5:1; preferably, the growth atmosphere during the deposition and growth of the first Si-doped GaN layer is a mixture of _N2 / _H2 / _NH3 with a ratio of 1:2:6; the growth atmosphere during the deposition and growth of the superlattice layer is a mixture of _N2 / _NH3 with a ratio of 1:3. The growth pressure during the growth of the composite N-type GaN layer is 50torr-300torr; preferably, the growth pressure during the growth of the composite N-type GaN layer is 150torr.

For the LED structure grown from sapphire as a substrate, since the resistivity of the N-type GaN layer is higher than that of the transparent electrode on the P-type GaN, it is the main factor affecting the current expansion of the device and increasing the series resistance. The light-emitting diode preparation method provided by the present invention deposits a first Si-doped GaN layer with a higher concentration on the non-doped GaN layer, which can generate a large number of electrons to supply the multi-quantum well layer, and radiate and recombine with the holes in the multi-quantum well layer, thereby reducing the overall resistivity of the composite N-type GaN layer and improving the light-emitting effect of the diode. In addition, the first Si-doped GaN layer is deposited to a thickness of 1um-5um. The higher thickness can increase the current expansion, reduce the series resistance of the composite N-type GaN layer, and reduce the operating voltage of the light-emitting diode. It can also release the compressive stress inside the composite N-type GaN layer through stacking faults, reduce line defects, improve crystal quality, and reduce reverse leakage current.

Furthermore, a SiN layer is deposited on the first Si-doped GaN layer, and a dense SiN film can be formed on the first Si-doped GaN layer to block dislocation defects that penetrate the first Si-doped GaN layer, and further reduce the extension of dislocation defects to the multi-quantum well layer, which affects the luminescence efficiency of the multi-quantum well layer. In addition, the superlattice layer includes a Si-doped AlN layer, an InN layer, and a second Si-doped GaN layer that are alternately deposited on the SiN layer in sequence according to a preset period. Preferably, the thickness ratio of the Si-doped AlN layer, the InN layer, and the second Si-doped GaN layer is 1:1:10~10:1:50, and the period of alternating deposition is 1-20. The superlattice layer can effectively release the mismatch stress between the composite N-type GaN layer 40 and the multi-quantum well layer, improve the incorporation efficiency of electrons and holes in the multi-quantum well layer, improve the crystal quality, and reduce the non-radiative recombination efficiency of the multi-quantum well layer. Furthermore, the Si-doping concentration of the second Si-doped GaN layer in the superlattice layer is lower than that of the first Si-doped GaN layer, which can provide a movement channel for the electrons generated by the first Si-doped GaN layer, so that the electrons can effectively move to the multi-quantum well layer, which can reduce the interface voltage between the second Si-doped GaN layer and the multi-quantum well layer, and further improve the crystal quality.

Step S60 , depositing a multi-quantum well layer on the composite N-type GaN layer.

Specifically, the multi-quantum well layer is an alternately deposited InGaN quantum well layer and an AlGaN quantum barrier layer, with a deposition cycle number of 6 to 12, preferably, a deposition cycle of 10. The InGaN quantum well layer has a growth temperature of 790°C to 810°C, a thickness of 2nm to 5nm, a growth pressure of 50torr to 300torr, and an In component of 0.15-0.3; preferably, the InGaN quantum well layer has a growth temperature of 795°C, a thickness of 3.5nm, a growth pressure of 200torr, and an In component of 0.22. The AlGaN quantum barrier layer has a growth temperature of 800°C to 900°C, a thickness of 5nm to 15nm, a growth pressure of 50torr to 300torr, and an Al component of 0.01 to 0.1; preferably, the AlGaN quantum barrier layer has a growth temperature of 855°C, a thickness of 9.8nm, a growth pressure of 200 torr, and an Al component of 0.05. The multi-quantum well layer is the region where electrons and holes radiate and recombine. Reasonable structural design can significantly increase the overlap of electron and hole wave functions, thereby improving the luminous efficiency of LED devices.

Step S70, depositing an electron blocking layer on the multi-quantum well layer.

Specifically, the electron blocking layer is an Al _a In _b GaN layer, the thickness of the electron blocking layer is 10nm~40nm, the growth deposition temperature is 900℃-1000℃, the pressure is 100torr~300torr, the Al component is 0.005<a<0.1, and the In component concentration is 0.01<b<0.2. Preferably, the thickness of the electron blocking layer is 15 nm, the growth deposition temperature is 965℃, the pressure is 200torr, the Al component concentration gradually changes from 0.01 to 0.05 along the growth direction of the epitaxial layer, and the In component concentration is 0.01. The electron blocking layer can effectively limit the electron overflow, reduce the blocking of holes, improve the injection efficiency of holes into the quantum well, reduce carrier Auger recombination, and improve the luminous efficiency of the light-emitting diode.

Step S80, depositing a P-type GaN layer on the electron blocking layer.

Specifically, the main function of the P-type GaN layer is to provide holes for the multi-quantum well layer, so that electrons and holes in the multi-quantum well layer can be radiatively recombined to emit light. The growth temperature of the P-type GaN layer is 900℃-1050℃, the thickness is 10nm~50nm, the growth pressure is 100torr~600torr, and Mg is used for doping, and the doping concentration is 1×10 ¹⁹ atoms/cm ³ ~1×10 ²¹ atoms/cm ^3. Too high Mg doping concentration will damage the crystal quality, while too low doping concentration will affect the hole concentration. Preferably, the growth temperature of the P-type GaN layer is 985℃, the thickness is 15nm, the growth pressure is 200torr, and the Mg doping concentration is 2×10 ²⁰ atoms/cm ^3. At the same time, for LED structures containing V-shaped pits, the higher growth temperature of the P-type GaN layer is also conducive to merging the V-shaped pits to obtain LED epitaxial wafers with smooth surfaces.

Example 1

A high-efficiency light-emitting diode, in this embodiment, a sapphire substrate is selected. The thicknesses of the first Si-doped GaN layer, the SiN layer and the superlattice layer are 2.5um/1nm/200nm respectively, the thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1:1:4, the cycle of the alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 6, the concentration of Si doped in the first Si-doped GaN layer is 1×10 ¹⁹ atoms/cm ³ , the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 1×10 ¹⁷ atoms/cm ³ , the N ₂ /H ₂ /NH ₃ composition ratio of the first Si-doped GaN layer is 1:1:10, and the N ₂ /NH ₃ composition ratio of the superlattice layer is 1:5.

Example 2

The high-efficiency light-emitting diode in this embodiment is different from the light-emitting diode in Embodiment 1 in that the thicknesses of the first Si-doped GaN layer, the SiN layer and the superlattice layer are 5 um/80 nm/50 nm respectively, the thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 5:1:40, the period of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1, the concentration of Si doped in the first Si-doped GaN layer is 5×10 ¹⁹ atoms/cm ³ , the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 6×10 ¹⁷ atoms/cm ³ , the N ₂ /H ₂ /NH ₃ composition ratio of the first Si-doped GaN layer is 1:3:10, and the N ₂ /NH ₃ composition ratio of the superlattice layer is 1:2.

Example 3

The high-efficiency light-emitting diode in this embodiment is different from the light-emitting diode in Embodiment 1 in that the thicknesses of the first Si-doped GaN layer, the SiN layer and the superlattice layer are 2 um/50 nm/200 nm respectively, the thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1:1:10, the cycle of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 6, the concentration of Si doped in the first Si-doped GaN layer is 2×10 ¹⁹ atoms/cm ³ , the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 3×10 ¹⁷ atoms/cm ³ , the N ₂ /H ₂ /NH ₃ composition ratio for growing the first Si-doped GaN layer is 1:1:8, and the N ₂ /NH ₃ composition ratio for growing the superlattice layer is 1:5.

Example 4

The high-efficiency light-emitting diode in this embodiment is different from the light-emitting diode in Embodiment 1 in that the thicknesses of the first Si-doped GaN layer, the SiN layer and the superlattice layer are 3 um/65 nm/300 nm respectively, the thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 10:1:30, the cycle of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 8, the concentration of Si doped in the first Si-doped GaN layer is 2×10 ¹⁹ atoms/cm ³ , the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 6×10 ¹⁷ atoms/cm ³ , the N ₂ /H ₂ /NH ₃ composition ratio of the first Si-doped GaN layer is 1:2:10, and the N ₂ /NH ₃ composition ratio of the superlattice layer is 1:1.

Example 5

The high-efficiency light-emitting diode in this embodiment is different from the light-emitting diode in Embodiment 1 in that the thicknesses of the first Si-doped GaN layer, the SiN layer and the superlattice layer are 2.5 um/45 nm/200 nm respectively, the thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1:1:40, the cycle of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 6, the concentration of Si doped in the first Si-doped GaN layer is 2×10 ¹⁹ atoms/cm ³ , the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 1×10 ¹⁸ atoms/cm ³ , the N ₂ /H ₂ /NH ₃ composition ratio of the first Si-doped GaN layer is 1:3:8, and the N ₂ /NH ₃ composition ratio of the superlattice layer is 1:4.

Example 6

The high-efficiency light-emitting diode in this embodiment is different from the light-emitting diode in Embodiment 1 in that the thicknesses of the first Si-doped GaN layer, the SiN layer and the superlattice layer are 3 um/100 nm/80 nm respectively, the thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1:1:6, the cycle of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 3, the concentration of Si doped in the first Si-doped GaN layer is 1×10 ²⁰ atoms/cm ³ , the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 1×10 ¹⁹ atoms/cm ³ , the N ₂ /H ₂ /NH ₃ composition ratio for growing the first Si-doped GaN layer is 1:2:6, and the N ₂ /NH ₃ composition ratio for growing the superlattice layer is 4:1.

Example 7

The high-efficiency light-emitting diode in this embodiment is different from the light-emitting diode in Embodiment 1 in that the thicknesses of the first Si-doped GaN layer, the SiN layer and the superlattice layer are 3.5 um/85 nm/500 nm respectively, the thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 10:1:50, the period of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 10, the concentration of Si doped in the first Si-doped GaN layer is 2×10 ¹⁹ atoms/cm ³ , the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 8×10 ¹⁷ atoms/cm ³ , the N ₂ /H ₂ /NH ₃ composition ratio for growing the first Si-doped GaN layer is 1:5:10, and the N ₂ /NH ₃ composition ratio for growing the superlattice layer is 3:1.

Example 8

The high-efficiency light-emitting diode in this embodiment is different from the light-emitting diode in Embodiment 1 in that the thicknesses of the first Si-doped GaN layer, the SiN layer and the superlattice layer are 2 um/65 nm/200 nm respectively, the thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 10:1:30, the cycle of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 20, the concentration of Si doped in the first Si-doped GaN layer is 8×10 ¹⁸ atoms/cm ³ , the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 3×10 ¹⁷ atoms/cm ³ , the N ₂ /H ₂ /NH ₃ composition ratio of the first Si-doped GaN layer is 1:4:10, and the N ₂ /NH ₃ composition ratio of the superlattice layer is 5:1.

Example 9

The high-efficiency light-emitting diode in this embodiment is different from the light-emitting diode in Embodiment 1 in that the thicknesses of the first Si-doped GaN layer, the SiN layer and the superlattice layer are 1 um/65 nm/300 nm respectively, the thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1:1:5, the cycle of alternating deposition of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 9, the concentration of Si doped in the first Si-doped GaN layer is 1×10 ¹⁸ atoms/cm ³ , the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 2×10 ¹⁷ atoms/cm ³ , the N ₂ /H ₂ /NH ₃ composition ratio for growing the first Si-doped GaN layer is 1:1:6, and the N ₂ /NH ₃ composition ratio for growing the superlattice layer is 2:1.

Comparative Example

The light emitting diode in this embodiment is different from the high-efficiency light emitting diode in embodiment 1 in that an N-type GaN layer is inserted between the undoped GaN layer and the multi-quantum well layer. The N-type GaN layer is 3 um thick and is doped with Si at a doping concentration of 2×10 ¹⁹ atoms/cm ³ .

Please refer to Table 1, which shows the comparison of some parameters of the above-mentioned embodiments and control examples and the comparison results of the corresponding light transmittance.

Table 1

As can be seen from Table 1, the photoelectric efficiency of the high-efficiency light-emitting diode epitaxial wafer provided by the present invention is improved by 1.5%-5% compared with the light-emitting diode epitaxial wafer currently prepared in mass production.

It should be noted that the above implementation process is only to illustrate the feasibility of the present application, but it does not mean that the high-efficiency light-emitting diode of the present application has only the above-mentioned implementation processes. On the contrary, as long as the high-efficiency light-emitting diode of the present application can be implemented, it can be included in the feasible implementation scheme of the present application. In addition, the structural part of the high-efficiency light-emitting diode in the embodiment of the present invention corresponds to the method for preparing the high-efficiency light-emitting diode of the present invention, and the specific implementation details are also the same, which will not be repeated here.

In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.

Claims (10)

1. A high-efficiency light-emitting diode, characterized in that it comprises a substrate, and a buffer layer, an undoped GaN layer, a composite N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer sequentially deposited on the substrate; The composite N-type GaN layer includes a first Si-doped GaN layer, a SiN layer and a superlattice layer sequentially deposited on the undoped GaN layer, and the superlattice layer includes a Si-doped AlN layer, an InN layer and a second Si-doped GaN layer alternately deposited in sequence according to a preset period, wherein the concentration of Si doped in the first Si-doped GaN layer is greater than the concentration of Si doped in the second Si-doped GaN layer. 2. The high-efficiency light-emitting diode according to claim 1 is characterized in that the thickness of the first Si-doped GaN layer is 1um-5um, the thickness of the SiN layer is 1nm-100nm, and the thickness of the superlattice layer is 50nm-500nm. 3 . The high-efficiency light-emitting diode according to claim 1 , wherein a thickness ratio of the Si-doped AlN layer, the InN layer and the second Si-doped GaN layer is 1:1:10 to 10:1:50. The high-efficiency light-emitting diode according to claim 1 , wherein the preset period is 1-20. The high-efficiency light-emitting diode according to claim 1, characterized in that the concentration of Si doped in the first Si-doped GaN layer is 1×10 ¹⁸ atoms/cm ³ -1×10 ²⁰ atoms/cm ³ , and the concentration of Si doped in the Si-doped AlN layer and the second Si-doped GaN layer is 1×10 ¹⁷ atoms/cm ³ -1×10 ¹⁹ atoms/cm ³ . 6. A method for preparing the high-efficiency light-emitting diode according to any one of claims 1 to 5, characterized in that the preparation method comprises the following steps: providing a substrate; Depositing a buffer layer, a non-doped GaN layer, a composite N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer in sequence on the substrate; The composite N-type GaN layer includes a first Si-doped GaN layer, a SiN layer and a superlattice layer sequentially deposited on the undoped GaN layer, and the superlattice layer includes a Si-doped AlN layer, an InN layer and a second Si-doped GaN layer alternately deposited on the SiN layer in sequence according to a preset period, wherein the concentration of Si doped in the first Si-doped GaN layer is greater than the concentration of Si doped in the second Si-doped GaN layer. 7 . The preparation method according to claim 6 , wherein the growth atmosphere during the deposition and growth of the first Si-doped GaN layer is a mixed gas with a composition ratio of N ₂ /H ₂ /NH ₃ of 1:1:10-1:5:10. 8 . The preparation method according to claim 6 , wherein the growth atmosphere during the deposition growth of the superlattice layer is a mixed gas with a N ₂ /NH ₃ composition ratio of 1:5-5:1. 9. The preparation method according to claim 6 is characterized in that: the deposition growth temperature of the first Si-doped GaN layer is 1000°C-1200°C, the deposition growth temperature of the SiN layer is 900°C-1100°C, and the deposition growth temperature of the superlattice layer is 800°C-1000°C. 10 . The preparation method according to claim 6 , wherein the growth pressure during the growth of the composite N-type GaN layer is 50 torr-300 torr.

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